.\" Copyright (c) 2002,2003 Alexey Zelkin <phantom@FreeBSD.org>
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.\" Copyright (c) 2024 The FreeBSD Foundation
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.\" Portions of this documentation were written by Olivier Certner
.\" <olce@FreeBSD.org> at Kumacom SARL under sponsorship from the
.\" FreeBSD Foundation.
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.Dd January 5, 2024
.Dt PTHREAD_ATTR_GET_NP 3
.Os
.Sh NAME
.Nm pthread_attr_get_np
.Nd get attributes of an existing thread
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread_np.h
.Ft int
.Fn pthread_attr_get_np "pthread_t pid" "pthread_attr_t *dst"
.Sh DESCRIPTION
The
.Fn pthread_attr_get_np
function is used to retrieve the attributes of the specified thread into an
existing
.Vt pthread_attr_t
structure.
The attributes' values are the current ones for the target thread, except for
the stack top address if not properly aligned for the architecture, since in
this case its value has been adjusted internally before use.
.Pp
Argument
.Fa dst
must be a pointer to a valid attributes object
.Po
it was initialized at some point by
.Xr pthread_attr_init 3
and was not destroyed since then
.Pc .
After a successful call to
.Fn pthread_attr_get_np ,
the individual attributes' values can be retrieved as usual via the
corresponding accessor functions as documented in
.Xr pthread_attr 3 .
After a failed call to
.Fn pthread_attr_get_np ,
the object pointed to by
.Fa dst
is left unmodified, and can continue to be used as if the failed call never
happened.
.Sh RETURN VALUES
If successful,
.Fn pthread_attr_get_np
function returns 0.
Otherwise, an error number is returned to indicate the error.
.Sh EXAMPLES
This function retrieves the stack size of the thread specified by the
.Fa pid
argument:
.Bd -literal
size_t
my_thread_stack_size(pthread_t tid)
{
	pthread_attr_t attr;
	size_t size;

	pthread_attr_init(&attr);
	pthread_attr_get_np(tid, &attr);
	pthread_attr_getstacksize(&attr, &size);
	pthread_attr_destroy(&attr);
	return (size);
}
.Ed
.Sh ERRORS
The
.Fn pthread_attr_get_np
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
One of the arguments has an invalid value.
.It Bq Er ESRCH
No thread could be found corresponding to that specified by the given
thread ID.
.It Bq Er ENOMEM
There was not enough memory to allocate additional storage needed by the attributes
object's implementation.
.El
.Sh SEE ALSO
.Xr pthread_attr 3 ,
.Xr pthread_attr_destroy 3 ,
.Xr pthread_attr_getdetachstate 3 ,
.Xr pthread_attr_getinheritsched 3 ,
.Xr pthread_attr_getschedparam 3 ,
.Xr pthread_attr_getschedpolicy 3 ,
.Xr pthread_attr_getscope 3 ,
.Xr pthread_attr_getstack 3 ,
.Xr pthread_attr_getstackaddr 3 ,
.Xr pthread_attr_getstacksize 3 ,
.Xr pthread_attr_init 3 ,
.Xr pthread_np 3
.Sh AUTHORS
The
.Fn pthread_attr_get_np
function and this manual page were written by
.An Alexey Zelkin Aq Mt phantom@FreeBSD.org ,
and the latter was revised by
.An Olivier Certner Aq Mt olce@FreeBSD.org .
